This invention relates to combination or permutation locks and is more particularly concerned with locks in which the user can conveniently change the combination that unlocks the lock.
Combination locks which permit the user to change the combination are well known. See, for example, U.S. Pat. No. 4,123,923 to Bako, issued Nov. 7, 1978 (assigned to the same assignee as the present invention) and the patents referred to therein. The Bako patent discloses a combination lock that is frontprogrammable. In other words, the user can change the combination of the lock from the front of the lock and thus avoid the inconvenience of prior locks in which the combination is changed from the back of the lock only after opening of a luggage case, for example, on which the lock is mounted. To change the combination of the lock of the Bako patent, the user sets the combination dials on-combination (i.e., at the unlocking combination) and moves a manual actuator in a predetermined direction to release a spring-biased hasp. This exposes a plunger that, when depressed, permits the manual actuator to move further in the predetermined direction to a combination-changing position at which the dials can be rotated relative to corresponding locking sleeves to change the combination.
More recently, as disclosed, for example, in U.S. Pat. No. 4,389,863, issued June 28, 1983 and assigned to the same assignee as the present invention, front-programmable combination locks are known in which a separate shift member exposed through a faceplate opening of the lock may be operated after the lock has been set on-combination to permit the combination to be changed.